Abstract
Cervical fusion has been a standard procedure for treating abnormalities associated with the cervical spine. However, the reliability of anterior cervical discectomy and fusion (ACDF) has become arguable due to its adverse effects on the biomechanics of adjacent segments. One of the drawbacks associated with ACDF is adjacent segment degeneration (ASD), which has served as the base for the development of dynamic stabilization systems (DSS) and total disc replacement (TDR) devices for cervical spine. However, the hybrid surgical technique has also gained popularity recently, but its effect on the biomechanics of cervical spine is not well researched. Thus, the objective of this FE study was to draw a comparison among single-level, bi-level, and hybrid surgery with dynamic cervical implants (DCIs) with traditional fusion. Reductions in the range of motion (ROM) for all the implanted models were observed for all the motions except extension, compared to for the intact model. The maximum increase in the ROM of 42% was observed at segments C5–C6 in the hybrid DCI model. The maximum increase in the adjacent segment’s ROM of 8.7% was observed in the multilevel fusion model. The maximum von Mises stress in the implant was highest for the multilevel DCI model. Our study also showed that the shape of the DCI permitted flexion/extension relatively more compared to lateral bending and axial rotation.
Highlights
Published: 4 January 2022Cervical disc degenerative diseases are often treated with traditional anterior cervical discectomy and fusion (ACDF)
This study used computational analysis to draw a comparison among single-level dynamic cervical implants (DCIs), bi-level DCI, and hybrid DCI configurations with single- and bi-level fusion
Our biomechanical finite element (FE) study suggested that the DCI may be a good alternate to ACDF, but it had its own limitations
Summary
Cervical disc degenerative diseases are often treated with traditional anterior cervical discectomy and fusion (ACDF). ACDF leads to the loss of motion at the index segment which is compensated by adjacent segments [1]. The traditional cervical fusion procedure has been under question in recent decades, as studies have reported high rates of adjacent segment degeneration (ASD) following fusion surgery [2]. Motionpreserving devices are being explored by clinicians that may restore motion at the index segment and reduce the chances of developing ASD [2,3,4,5,6]. Dynamic stabilization systems (DSS) and total disc replacement (TDR) implants are commonly used as motion-preserving devices [7,8,9]. TDR implants have been usually associated with the hypermobility at the index segment and causing strain to the surrounding ligaments [10,11]
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